NERITOPSIS. 341 



restricted in this country to the Parkinsoni-zone of Burton Bradstock, where it 

 occasionally attains a large size. 



273. Neritopsis Phtlea, d'Orbigny, 1850. Inferior Oolite variety, Plate XXVII, 



figs. 11a, 116, 11 c. 



1850. Neritopsis Philea, d'Orbigny. Prod., i, p. 247. 



1852. — — — Terr. Jur., vol. ii, p. 222, pi. ccc, figs. 5— 7. 



Cf. also — Bajocensis, d'Orb. Hudleston, Geol. Mag., dec. 3, vol. i, 



p. 300, pi. ix, fig. 11 (Dogger variety). 



The Dogger specimen above referred to was described by me as an intermediate 

 form, and it belongs to the variety figured on the accompanying plate (XXVII, 

 11), which is the prevailing form in the Concavus-bed at Bradford Abbas, where it 

 sometimes attains a width of nearly 40 mm. It has the flattened shoulder and 

 spiral ornamentation of Neritopsis Philea, and is devoid of the thick radial costse 

 so characteristic of N. Bajocensis. The " rampe posterieur," however, is scarcely 

 developed in this variety, and the ornamentation generally is finer. Occasionally 

 a specimen which corresponds almost exactly with d'Orbigny's figure and 

 description may be found in the Concavus-bed. To these the name N. Philea may 

 be applied without hesitation. If it is desirable to recognise the variety I would 

 suggest Neritopsis Philea, var. Abbas. 



274. Neritopsis varicosa, Morris and Lycett, 1851. Plate XXVIII, figs. 1 a, 1 b, 1 c. 



1851. Neritopsis varicosa, Morris and Lycett. Great Ool. Moll., pt. i, p. 106, 



pi. xi, figs. 20, 20 a; pi. xiii, 

 fig. 5. 



1854. — — — Morris, Cat., p. 265. 



Description : 



Height of a full-sized specimen . . 13'5 mm. 



Width ..... 16-5 mm. 

 The following is the diagnosis by the authors : — " Shell neritiform, ovately 

 oblong; varices large, longitudinal (about ten in a volution), more or less elevated, 

 decussated, with numerous regular, elevated, and transverse (spiral) lines ; the 

 lines are impressed with extremely fine and dense perpendicular striae; the 

 aperture round." 



Relations and Distribution. — This species is related to N. Bajocensis, from 



44 



